The message, it seems, has finally gotten through: global warming represents a serious threat to our planet. At the recent World Economic Forum in Davos, world leaders saw climate change, for the first time, topping the list of global concerns.

Europe and Japan have shown their commitment to reduce global warming by imposing costs on themselves and their producers, even if it places them at a competitive disadvantage. The biggest obstacle until now has been the United States. The Clinton administration had called for bold action as far back as 1993, proposing what was in effect a tax on carbon emissions; but an alliance of polluters, led by the coal, oil, and auto industries beat back this initiative.

To the scientific community, the evidence on climate change has, of course, been overwhelming for more than a decade and a half. I participated in the second assessment of the scientific evidence conducted by the Intergovernmental Panel on Climate Change, which perhaps made one critical mistake: it underestimated the pace at which global warming was occurring. The Fourth Assessment, which was just issued, confirms the mounting evidence and the increasing conviction that global warming is the result of the increase in greenhouse gases in the atmosphere.

The increased pace of warming reflects the impact of complex non-linear factors and a variety of "tipping points" that can result in acceleration of the process. For instance, as the Arctic ice cap melts, less sunlight is reflected. Seemingly dramatic changes in weather patterns - including the melting of glaciers in Greenland and the thawing of the Siberian permafrost - have at last convinced most business leaders that the time for action is now.

Recently, even President Bush seems to have woken up. But a closer look at what he is doing, and not doing, shows clearly that he has mostly heard the call of his campaign contributors from the oil and coal industries, and that he has once again put their interests over the global interest in reducing emissions. If he were truly concerned about global warming, how could he have endorsed the construction of coal-fired electricity plants, even if those plants use more efficient technologies than have been employed in the past?

What is required, first and foremost, are market-based incentives to induce Americans to use less energy and to produce more energy in ways that emit less carbon. But Bush has neither eliminated massive subsidies to the oil industry (though, fortunately, the Democratic Congress may take action) nor provided adequate incentives for conservation. Even his call for energy independence should be seen for what it is - a new rationale for old corporate subsidies.

A policy that entails draining America's limited oil supplies - I call it "drain America first" - will leave the US even more dependent on foreign oil. The US imposes a tariff of more than 50 cents per gallon on sugar-based ethanol from Brazil, but subsidises inefficient corn-based American ethanol heavily - indeed , it requires more than a gallon of gasoline to fertilise, harvest, transport, process, and distil corn to yield one gallon of ethanol.

As the world's largest polluter, accounting for roughly a quarter of global carbon emissions, America's reluctance to do more is perhaps understandable, if not forgivable. But claims by Bush that America cannot afford to do anything about global warming ring hollow: other advanced industrial countries with comparable standards of living emit only a fraction of what the US emits per dollar of GDP.

As a result, American firms with access to cheap energy are given a big competitive advantage over firms in Europe and elsewhere. Some in Europe worry that stringent action on global warming may be counterproductive: energy-intensive industries may simply move to the US or other countries that pay little attention to emissions. And there is more than a grain of truth to these concerns.

A striking fact about climate change is that there is little overlap between the countries that are most vulnerable to its effects - mainly poor countries in the South that can ill afford to deal with the consequences - and the countries, like the US, that are the largest polluters. What is at stake is in part a moral issue, a matter of global social justice.

The Kyoto Protocol represented the international community's attempt to begin to deal with global warming in a fair and efficient way. But it left out a majority of the sources of emissions, and unless something is done to include the US and the developing countries in a meaningful way, it will be little more than a symbolic gesture. There needs to be a new "coalition of the willing," this time perhaps led by Europe - and this time directed at a real danger.

This "coalition of the willing" could agree to certain basic standards: to forego building coal-fired plants, increase automobiles' fuel efficiency, and provide targeted assistance to developing countries to enhance their energy efficiency and reduce emissions. Coalition members could also agree to provide stronger incentives to their own producers, through either more stringent caps on emissions or higher taxes on pollution. They could then agree to impose taxes on products from other countries - including the US - that are produced in ways that unnecessarily add substantially to global warming. What is at stake is not protecting domestic producers, but protecting our planet.

The changing climate on climate change provides political leaders in Europe and other potential members of this "coalition of the willing" an unprecedented opportunity to move beyond mere rhetoric. The time to act is now.